New macOS Backdoor Linked to Cyber-espionage Group

A recently discovered macOS backdoor is believed to be a new version of malware previously associated with the OceanLotus cyber-espionage group, Trend Micro says.

Also known as APT 32, APT-C-00, SeaLotus, and Cobalt Kitty, OceanLotus is believed to be operating out of Vietnam and has been targeting high-profile corporate and government organizations in Southeast Asia. Well-resourced and determined, the group uses custom-built malware and already established techniques.

Some of the group’s targets include human rights organizations, media organizations, research institutes, and maritime construction firms.

The newly discovered macOS backdoor, which Trend Micro detects as OSX_OCEANLOTUS.D, has been observed on machines that have the Perl programming language installed.

The malware is being distributed via malicious documents attached to emails. The document masquerades as the registration form for an event with HDMC, an organization in Vietnam that advertises national independence and democracy.

The document contains malicious, obfuscated macros with a payload written in Perl. The macro extracts an XML file from the Word document. This file is an executable acting as the dropper for the final payload, which is the backdoor.

The dropper, which has all of its strings encrypted using a hardcoded RSA256 key, is also used to establish the backdoor’s persistence on the infected systems. The dropper checks whether it runs as root or not, and uses different path and filename based on that.

The dropper sets the backdoor’s attributes to “hidden” and uses random values for the file date and time, and deletes itself at the end of the process.

The backdoor has two main functions, which collect platform information and sending it to the command and control (C&C) server. It can also receive additional C&C communication information, which is encrypted before being sent.

“Malicious attacks targeting Mac devices are not as common as its counterparts, but the discovery of this new macOS backdoor that is presumably distributed via phishing email calls for every user to adopt best practices for phishing attacks regardless of operating system,” Trend Micro concludes.